The present invention relates to a system and device for low power consumption of on/off control of a single or a plurality of electronic ballasts that can be used for a variety of lighting functions.
Electronic ballasting of gas discharge lighting has become the leading option over passive reactive ballasting. Gas discharging lighting includes fluorescent and high intensity discharge (HID) lamps. Electronic ballasts are constructed with active electronic components such as transistors that allow functional electrical control. The normal operation of the ballasted lights requires them to be energized or de-energized corresponding to xe2x80x9con and offxe2x80x9d operation. This is usually accomplished by an external mechanical switch, which applies or interrupts electrical power to the ballast and corresponding causes the lamp(s) to go on or off.
The ballast operating current and voltage that powers the ballast must be experienced by this power switch which for safety reasons is under restrictions governed by building code wiring requirements for safety. Because of the special knowledge associated with such power wiring a costly professional electrician is normally required to alter any switching control within a given building space.
There are a number of limitations associated with this common means for on/off control. First the control switch must support the current requirements of all the lighting in a given area, so for large areas, the current carrying capacity of the switch must be raised to accommodate the greater load currents of the lighting. When this happens the power switching arrangement becomes complex with power switching implemented through a combination of mechanical and electric relays (contactors) that increase to hardware needs, increase expense and reduced reliability of the system.
Another limitation occurs if the switch is very remote and distant for the lights, requiring the lighting load current to pass to and from the remote switch causing an undesirable electrical loss corresponding to resistive voltage drops. Additionally, such a system is inflexible to alterations and modifications, essentially requiring the special training and experience of higher cost electric contract service assistance, to alter a switching arrangement, or to add automated remote functions to the lights.
It is therefore an object of this invention to cause a ballast to be energized in satisfaction of the xe2x80x9con/offxe2x80x9d control, by an ultra low power controller that may be essentially isolated for primary power circuit or derive its very low switch power from the ballast itself. With this invention it is possible to effect on/off control with the lowest voltage and current for an essentially near lossless control means. The invention can be used with lighting ballasts, but also for any devices with on/off switches, such as motors, appliances, heaters and the like.
It is also an object of this invention to use its on/off control means to effect other desirable functions in the electric ballast. Such functions include but are not limited to electronic action that would cause the electronic ballast to operate at fractional power levels corresponding to different lighting intensities and/or with conventional occupancy sensors.
It is a further object of this invention to utilize wiring components in the on/off control that correspond to the domain of signal or control wiring and which are characterized by very low power requirements and do not have the restrictions associated with power wiring. Such wiring is common in the telecommunications industry and may be applied to external programmed control.
In keeping with these objects and others which may become apparent, the present invention is a ballast or power electronics module which is controlled by a remotely located switch function with a low amount of control current and little power loss. This is effected by means of a photo-isolator interfacing circuit within the ballast or within the power electronics module that provides high electrical isolation between an external control signal current and the power electronics of the ballast. The photo-isolator is the switch interface from signal level to power level control.
The on/off switching system can be used for one or more electronic ballasts for one or more lamps, of one or more lighting fixtures. The system includes the one or more ballasts having power electronics, wherein the system further includes a remote switch function in each ballast, which remote switch function is remotely located apart from each ballast. The remote switch function operates with a low amount of control current and little power loss. This on/off switching system further includes one or more connections connecting the remotely located switch to a ballast resident opto-isolator circuit, with associated interfacing electronics within each ballast. Therefore, each ballast provides high electrical isolation between the external switch function and the ballast power electronics to each lamp.
Besides its use with lighting ballasts, the remote on/off switching function system can also be used for one or more electronically interfaceable end-use appliance devices which function through on/off control. For example, the devices can include motors, heaters, appliances, industrial electrical equipment or other appliances which benefit from proportional on/off control as a means for power modulations. In these embodiments for other devices, each device has an on/off switch function, as well as power electronics, wherein the remote switch function is remotely located apart from the device""s resident power electronics, wherein further the remote switch function operates with a low amount of control current and little power loss. This on/off switching system further includes one or more connections connecting the remotely located switch function to an opto-isolator circuit with high electrical isolation to the power electronics. The power electronics provides electrical computability between the switch function and the operation of the device.
The remote on/off switching system can be applied for proportional light dimming control having as its interface an optically isolated on/off function interfacing with remote circuitry, providing pulse width modulation to the optically isolated interface control, to cause proportional light dimming. The remote circuitry includes a fixed frequency oscillator influenced by a pulse-width modulator controlled by a voltage setting, wherein proportional pulses cause constant current to flow remotely through a light emitting diode in an optical isolator in the electronic ballast, wherein a constant current driver insures a predetermined proper current to the light emitting diode in compensation for variable cable lengths. A phototransistor/switch of the optical isolator complies with the periodic xe2x80x9conxe2x80x9d duty cycle set remotely and causes the power in the ballast circuitry to be applied to the lamp with variable intensity.
A similar on/off switching system can be applied to one or more electrical end-use appliances compatible with electronic on/off control in which a similar optically isolating interface utilizing circuitry influences very low power remote control of power levied in the various end-use appliances such as motor driven devices, electrical heaters, industrial equipment and any other device that might benefit from proportional on/off control as a means for power modulation.
The singular switch can also control a plurality of ballasts including but not limited to ballasts applied to a plurality of HID or fluorescent lamps. This switching function can also be applied to programed interruption such as in controlled blinking functions which are used as an attraction in lighted advertising signs.
Optionally, an external repetitive control may be applied that causes the xe2x80x9conxe2x80x9d periods to be different from the xe2x80x9coffxe2x80x9d period such that power to the lamp is proportional to the on period. The said interface thus becomes a means for dimming with external singular functional control eliminating costly internal dimming control circuitry.
Furthermore, the external remote switch function may be provided through active electronic, such as, in part, a transistor. In addition, the remote switching function can be provided by a programmable electronic system, with or without feedback.
A plurality of lead wires connects the remote switch function, a low current power source, and the light emitting diode (LED) is available at the input of the opto-isolator. The low current power source can be derived from the ballast, or it can be supplied externally.
Although the connectors for the control of the ballast may be any signal type connector, a modular phone jack and plug and the use of the flat 4-conductor cable, common to telephone systems, as the plurality of lead wires facilitates installation.
Through the use of a common four wire 3-way RJ11 telephone coupler at each ballast and a length of flat 4-conductor telephone cable with reversed RJ11 plugs at each end (i.e. a reversed cable net) any number of ballasts can be connected in daisy-chain fashion to be controlled by a single remote switch. Adding, rerouting, or reconfiguring switches to control a network of light fixtures can be accomplished without the need of an electrician.
The electrically isolated photo-transistor portion of the opto-isolator is controlled by light emitted by the LED within the opto-isolator. The state of conduction of its collector-emitter junction is used to electronically control the operation (in an on/off fashion) of any standard high frequency electronic inverter circuitry used to derive AC power of any frequency to the fluorescent or HID lamps.